Suppression and recovery of GH secretion after GH injection in non-GH deficient short children

Effect of long-acting growth hormone treatment on endogenous growth hormone secretion in prepubertal patients with idiopathic short stature: A preliminary study

Long-acting growth hormone (LAGH) is emerging to be a new preparation for treatment of short stature. We aimed to determine whether 12-month treatment with LAGH in patients with idiopathic short stature has an effect on the nocturnal endogenous growth hormone (GH) secretion and metabolic consequences and efficacy. Participants included 10 GH-naïve prepubertal children with idiopathic short stature (ISS). One patient was withdrawn due to own decline during study. Participants were randomized on a 1:1 ratio to receive either a daily GH (0.37 mg/kg/week) or once-weekly LAGH (0.7 mg/kg/week) over a 12-month period. Nocturnal endogenous GH secretory profiles obtained from 12-h blood samplings at 30-min interval were assessed at baseline and 2 weeks after the completion of GH treatment. Post-treatment changes in height velocity, height standard deviation score (SDS), metabolic parameters, and adverse events were measured. A total of 4 patients received LAGH, and 5 patients received daily GH. Nocturnal endogenous GH secretory profiles, such as mean serum GH concentrations, frequency, amplitude, interpulse interval of spontaneous GH secretory bursts, and mass of GH released per secretory burst were similar at baseline and after 12-month treatment in both groups. The efficacy and safety after LAGH treatment for 12 months were similar to those of daily GH. In conclusions, these findings indicated that LAGH does not suppress endogenous GH secretion, and can be used for treatment of non-GH deficient short stature with similar efficacy and safety compared to daily GH. These may contribute to define and develop treatment and follow-up protocols for LAGH use in ISS patients.

Broad variability in pharmacokinetics of GH following rhGH injections in children

OBJECTIVE

Daily subcutaneous self-injection of GH is used worldwide to treat short stature in childhood; longitudinal data on the impact of this regimen on GH-uptake are lacking.

DESIGN

Children with/without GH-deficiency participating in clinical trials were followed prospectively (≤8 times). Blood was sampled pre-GH-injection (dose GH³³/GH⁶⁷ μg/kg) and either every 30 min thereafter for 24 h (Experimental-setting; 59 GH-curves/15 children); or every 2 h thereafter for 16 h (Clinical-setting; 429 GH-curves/117 children). Pharmacokinetics were estimated by time T_max (h) of maximal GH-concentration (C_max, mU/L) and area under the curve for 16 h (AUC, mU/L ∗ h).

RESULTS

In the Clinical-setting, median C_max was 71 mU/L and AUC was 534 mU/L ∗ h, with coefficients of variation for intra-individual variation of 39% and 36%, respectively, and inter-individual variation of 44% and 42%, respectively. 43% of C_max and AUC variability was explained by GH-dose and proxies for injection depth (baseline GH-level, GH_peakwidth, BMI_SDS). In the Experimental- versus Clinical-setting, 85% and 40% of GH-curves, respectively, reached zero-levels within 24 h. A longer duration was found following a more superficial GH-injection. Spontaneous GH-peaks were identified already 6 h after the GH-injection in about half of the curves of both GHD and non-GHD patients.

CONCLUSION

Very broad intra-individual and inter-individual variability was found. A high GH-peak will optimize growth effects; the highest C_max was found after a deep injection of GH at the higher dose and concentration. In as many as 60% of the children, GH remained detectable in serum after 24 h; a constant GH-level will promote IGF-I and metabolic effects.

Growth hormone dose-dependent pubertal growth: a randomized trial in short children with low growth hormone secretion

BACKGROUND/AIMS

Growth hormone (GH) treatment regimens do not account for the pubertal increase in endogenous GH secretion. This study assessed whether increasing the GH dose and/or frequency of administration improves pubertal height gain and adult height (AH) in children with low GH secretion during stimulation tests, i.e. idiopathic isolated GH deficiency.

METHODS

A multicenter, randomized, clinical trial (No. 88-177) followed 111 children (96 boys) at study start from onset of puberty to AH who had received GH 33 µg/kg/day for ≥1 year. They were randomized to receive 67 µg/kg/day (GH(67)) given as one (GH(67×1); n = 35) or two daily injections (GH(33×2); n = 36), or to remain on a single 33 µg/kg/day dose (GH(33×1); n = 40). Growth was assessed as heightSDSgain for prepubertal, pubertal and total periods, as well as AHSDS versus the population and the midparental height.

RESULTS

Pubertal heightSDSgain was greater for patients receiving a high dose (GH(67), 0.73) than a low dose (GH(33×1), 0.41, p < 0.05). AHSDS was greater on GH(67) (GH(67×1), -0.84; GH(33×2), -0.83) than GH(33) (-1.25, p < 0.05), and heightSDSgain was greater on GH(67) than GH(33) (2.04 and 1.56, respectively; p < 0.01). All groups reached their target heightSDS.

CONCLUSION

Pubertal heightSDSgain and AHSDS were dose dependent, with greater growth being observed for the GH(67) than the GH(33) randomization group; however, there were no differences between the once- and twice-daily GH(67) regimens. © 2014 S. Karger AG, Basel.

Inhaled growth hormone (GH) compared with subcutaneous GH in children with GH deficiency: pharmacokinetics, pharmacodynamics, and safety

BACKGROUND

Delivery of GH via inhalation is a potential alternative to injection. Previous studies of inhaled GH in adults have demonstrated safety and tolerability.

OBJECTIVE

We sought to assess safety and tolerability of inhaled GH in children and to estimate relative bioavailability and biopotency between inhaled GH and sc GH.

DESIGN/METHODS

This pediatric multicenter, randomized, double-blind, placebo-controlled, crossover trial had two 7-d treatment phases. Patients received inhaled GH and sc GH in the alternate phase. Placebo was administered by the route opposite from active drug. GH and IGF-I levels were measured at multiple time points. Pharmacokinetics were assessed using noncompartmental methods.

RESULTS

Twenty-two GH-deficient children aged 6-16 yr were treated. Absorption of GH appeared to be faster after inhalation with maximum serum concentrations measured at 1-4 h compared with 2-8 h for sc GH. Mean relative bioavailability for inhaled GH was 3.5% (90% confidence interval 2.7-4.4%). Mean relative biopotency, based on IGF-I response, was 5.5% (confidence interval 5.2-5.8%). Similar dose-dependent increases in mean serum GH area under the curve and IGF-I changes from baseline were seen after inhaled and sc GH doses. Inhaled GH was well tolerated and preferred to injection. No significant changes in pulmonary function tests were seen.

CONCLUSIONS

In this first pediatric trial of GH delivered by inhalation, it was well tolerated and resulted in dose-dependent increases in serum GH and IGF-I levels. This study establishes that delivery of GH via the deep lung is feasible in children.